Effects of low phosphorus stress on nitrogen and potassium absorbed and accumulated in rice shoot.

Pot experiments were conducted to investigate effects of low-P stress on nitrogen and potassium uptake and accumulation in Ptolerance rice genotypes 508,580,99011,99112,and P-sensitive rice genotypes 99012 and 99056.The result showed that low phosphorus stress had larger influence on nitrogen and potassium content of rice at tillering in low-P sensitive rice genotypes than in low-P tolerance rice genotypes.At booting stage,the potassium content of all supplied rice genotypes increased markedly under low phosphorus stress,and nitrogen content also increased markedly except 508.At both stages,the largest variation on nitrogen and potassium content was found in low-P sensitive rice genotype 99012,while the lowest was found in low-P sensitive rice genotype 99056.At maturity stage,low P stress had slight effects on nitrogen and potassium content for all rice genotypes due to the co-influence with absorbability and transportability.The accumulation of nitrogen and potassium was significantly higher in P-tolerance rice genotypes than in P-sensitive rice genotypes in the early growth stages.The difference of accumulation of nitrogen and potassium between two rice genotypes was declined,but the relative accumulation of nitrogen and potassium in P-tolerance rice genotypes increased in the latter growth stage.